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ipmi: Fix issues with BMC refcounts 

BMC device refcounts were not being decremented after fetching from
driver_find_device().  Also, document the use of ipmidriver_mutex
and tighten it's span some by incrementing the BMC's usecount in
the BMC find routines and not later.  This will be important for
future changes where a long mutex hold area will complicate things.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
This commit is contained in:
Corey Minyard 2017-09-01 12:52:20 -05:00
parent eae4a36a68
commit 9ca15af316
1 changed files with 35 additions and 16 deletions
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51
drivers/char/ipmi/ipmi_msghandler.c
View File

@ -526,6 +526,11 @@ static struct platform_driver ipmidriver = {
.bus = &platform_bus_type
}
};
/*
* This mutex protects adding/removing BMCs on the ipmidriver's device
* list. This way we can pull items out of the driver's list and reuse
* them.
*/
static DEFINE_MUTEX(ipmidriver_mutex);
static LIST_HEAD(ipmi_interfaces);
@ -2440,16 +2445,23 @@ static int __find_bmc_guid(struct device *dev, void *data)
return memcmp(to_bmc_device(dev)->guid, id, 16) == 0;
}
/*
* Must be called with ipmidriver_mutex held. Returns with the
* bmc's usecount incremented, if it is non-NULL.
*/
static struct bmc_device *ipmi_find_bmc_guid(struct device_driver *drv,
unsigned char *guid)
{
struct device *dev;
struct bmc_device *bmc = NULL;
dev = driver_find_device(drv, NULL, guid, __find_bmc_guid);
if (dev)
return to_bmc_device(dev);
else
return NULL;
if (dev) {
bmc = to_bmc_device(dev);
kref_get(&bmc->usecount);
put_device(dev);
}
return bmc;
}
struct prod_dev_id {
@ -2470,6 +2482,10 @@ static int __find_bmc_prod_dev_id(struct device *dev, void *data)
&& bmc->id.device_id == id->device_id);
}
/*
* Must be called with ipmidriver_mutex held. Returns with the
* bmc's usecount incremented, if it is non-NULL.
*/
static struct bmc_device *ipmi_find_bmc_prod_dev_id(
struct device_driver *drv,
unsigned int product_id, unsigned char device_id)
@ -2479,12 +2495,15 @@ static struct bmc_device *ipmi_find_bmc_prod_dev_id(
.device_id = device_id,
};
struct device *dev;
struct bmc_device *bmc = NULL;
dev = driver_find_device(drv, NULL, &id, __find_bmc_prod_dev_id);
if (dev)
return to_bmc_device(dev);
else
return NULL;
if (dev) {
bmc = to_bmc_device(dev);
kref_get(&bmc->usecount);
put_device(dev);
}
return bmc;
}
static void
@ -2514,8 +2533,8 @@ static void ipmi_bmc_unregister(ipmi_smi_t intf)
mutex_lock(&ipmidriver_mutex);
kref_put(&bmc->usecount, cleanup_bmc_device);
intf->bmc = NULL;
mutex_unlock(&ipmidriver_mutex);
intf->bmc = NULL;
}
static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
@ -2524,18 +2543,18 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
struct bmc_device *bmc = intf->bmc;
struct bmc_device *old_bmc;
mutex_lock(&ipmidriver_mutex);
/*
* Try to find if there is an bmc_device struct
* representing the interfaced BMC already
*/
mutex_lock(&ipmidriver_mutex);
if (bmc->guid_set)
old_bmc = ipmi_find_bmc_guid(&ipmidriver.driver, bmc->guid);
else
old_bmc = ipmi_find_bmc_prod_dev_id(&ipmidriver.driver,
bmc->id.product_id,
bmc->id.device_id);
mutex_unlock(&ipmidriver_mutex);
/*
* If there is already an bmc_device, free the new one,
@ -2546,9 +2565,6 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
intf->bmc = old_bmc;
bmc = old_bmc;
kref_get(&bmc->usecount);
mutex_unlock(&ipmidriver_mutex);
printk(KERN_INFO
"ipmi: interfacing existing BMC (man_id: 0x%6.6x,"
" prod_id: 0x%4.4x, dev_id: 0x%2.2x)\n",
@ -2558,14 +2574,17 @@ static int ipmi_bmc_register(ipmi_smi_t intf, int ifnum)
} else {
unsigned char orig_dev_id = bmc->id.device_id;
int warn_printed = 0;
struct bmc_device *tmp_bmc;
snprintf(bmc->name, sizeof(bmc->name),
"ipmi_bmc.%4.4x", bmc->id.product_id);
bmc->pdev.name = bmc->name;
while (ipmi_find_bmc_prod_dev_id(&ipmidriver.driver,
mutex_lock(&ipmidriver_mutex);
while ((tmp_bmc = ipmi_find_bmc_prod_dev_id(&ipmidriver.driver,
bmc->id.product_id,
bmc->id.device_id)) {
bmc->id.device_id))) {
kref_put(&tmp_bmc->usecount, cleanup_bmc_device);
if (!warn_printed) {
printk(KERN_WARNING PFX
"This machine has two different BMCs"